Infrared and terahertz dual band semiconductor development and spin orbitronics based on semiconductors and insulators
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
The rapid development of photoelectric detection technology calls for a new generation of semiconductor films working in both infrared and terahertz bands. We explored Ge1-xRx (R=Bi, Sn) dual band photoelectric devices. Through the doping of high Sn content, induced direct bandgap appears and the infrared light responsivity of the sample reaches to 0.60A/W at 2.2μm wavelength, and transmission in terahertz can be modulated. We have also successfully grown n-type GeBi semiconductor alloy thin films for the first time. The optimum Bi doping amount is between 2%-18%. Direct bandgap has also been induced with Bi doping that broaden the operation frequency at infrared. The GeBi films show a large light responsivity and the Bi-dopant dependent transmission at 0.3-0.8 THz terahertz. We have also fabricated Ge1-xSnx PIN and Ge1-yBiy PN devices working in both infrared and terahertz with relatively low dark current density, large modulation depth and fast modulation rate in terahertz from 0.1 to 1.0 THz. ☐ Bi dopants in semiconductors and insulators are known to introduce large spin orbit coupling, which has recently been applied in spin electronics, known as spintronics to produce pure spin currents to switch the magnetization in a magnetic layer. This has become an enabling technique to develop next generation non-volatile magnetic random-access memory (MRAM) or logic devices. The spin-orbit coupling in GeBi films was investigated by inject spin current via precessing the magnetization of a neighboring NiFe or Yttrium Iron Garnet (YIG) layer using ferromagnetic resonance. Large inverse spin Hall voltage has been observed due to the large SOC in GeBi layer. We further investigate the Bi doped magnetic insulator Thulium Iron Garnet (Bi:TmIG) to promote the out-of-plane magnetizations which is commonly used in spintronic applications. We have successfully grown single crystal and textured Bi:TmIG using liquid epitaxy and magnetron sputtering techniques. The current-induced spin orbital torques has been studied via the first- and second-order harmonic Hall voltage measurements in Bi:TmIG/Pt. The spin torque efficiency is much larger compared with metallic ferromagnet/Pt bilayer systems.
Description
Keywords
Applied sciences, Infrared and terahertz dual band semiconductor development, Insulators, Semiconductors, Spin orbitronics